That fixed it, thanks! I actually encountered this problem while working on
my own derived field that used ghost zones and was using VorticitySquared as
my example for how to do it. I think in the past it was not required to
list the fields with ValidateSpatial, which is why it was working as is in
older versions. I wasn't able to find documentation on how to make fields
that use ghost_zones. If it's in there and I just missed it, could someone
point me toward it? If not, I could add something to the Creating Derived
Fields section.

It looks like VorticitySquared wasn't specifying the necessary fields
(x,y,z velocity) in the definition. I will push a change momentarily after
I look around at any other ghost zone requiring fields to make sure they
work. DivV, for example, does the right thing.